During the implantation or insertion of medical devices such as catheters, pathogenic microbes may be introduced into the patient. Once implanted, microbes may attach to the surface of the device to form a biofilm, a common cause of device failure. To overcome these problems, several strategies have been used to create coatings that are either antimicrobial or nonfouling. Cheng et al. now report a coating that combines both properties, switching from antimicrobial to non-fouling upon hydrolysis. Specifically, they apply a poly(methacrylate) derivative with cationic side chains that become zwitterionic upon conversion of a terminal ester to a carboxylate. Within 1 hour of exposure to the initially prepared coating, 99.9% of attached Escherichia coti bacteria were dead. Over the course of the next 2 to 8 days, the coating slowly hydrolyzed, releasing 98% of the dead microbial cells. The nonfouling nature of the hydrolyzed coating prevents further attachment of microbial cells and formation of a biofilm. By tuning the hydrolysis rate of the coating, it should be possible to adapt it to a range of applications in implantable medical devices.
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